为什么不能用it is sure that,而可以it is certain that

为什么不能用it is sure that,而可以it is certain that I am sure (it) will be fine tomorrow 中的It 为什么不能用there替换?请说明点 It is all round the world为什么不能用around 高一英语34Before you leave the house , make sure it （be closed）这里为什么不能用closed ? is it a boy or a girl不是it不指的,为什么这里能用IT it sure is make sure that you will arrive there on time为什么不能用to make sure Why Thanks.为什么It's very cold,isn't it?的答案是It sure is.而不是It is sure. It is the hole in the ship,rather tha the floating iceberg,___ is to blame forIt is the hole in the ship,rather tha the floating iceberg,___ is to blame for the sunken ship in Antarctic.A.which B.this C.that D.whom请问为什么选C不选A谢谢 it is my friend ,Tom .为什么不能用he is my friend ,tom? the question is（ that if ）it is worth doing that if 为什么不能用在这里,只能用whether 为什么主句以be动词提问,所以从句连词不能用whether?例题：1.Are you sure _____?A.whether she is honest.B.she is honest. it sure is为什么这么写?有什么语法吗? who is that?it must be Mary.为什么不能用she? It is/was not until...that从句,为什么从句不能用when引导 The room is so dirty that it wants (cleaning )为什么不能用being cleaned it is only 5 meters away这里为什么不能用far? It is some time before i realize the turth.为什么用before而不能用until